Spina Bifida

Spina bifida is a birth defect that happens when a baby's backbone (spine) does not form normally. As a result, the spinal cord and the nerves that branch out of it may be damaged.

The term spina bifida comes from Latin and literally means "split" or "open" spine. This defect happens at the end of the first month of pregnancy, when a baby's spine and spinal cord (a bundle of nerves that runs down the center of the spine) are developing.

Sometimes, the defect causes an opening in the back, which is visible. The spinal cord and its coverings sometimes push through this opening. Other times, there is no opening and the defect remains hidden under the skin.

Depending on the severity of the defect and where it is on the spine, symptoms vary. Mild defects may cause few or no problems, while more severe defects can cause serious problems, including weakness, loss of bladder control, or paralysis.

Children with an exposed opening on the back will need surgery to close it.

Causes

Low levels of the vitamin folic acid during pregnancy are linked to spina bifida. Folic acid plays a large role in cell growth and development, as well as tissue formation. Not having enough folic acid in the diet before and during early pregnancy can increase a woman's risk of spina bifida and other neural tube defects.

The causes of spina bifida in pregnancies where mothers took prenatal vitamins and got enough folic acid are largely unknown. Some evidence suggests that genes may play a role, but most babies born with spina bifida have no family history of the condition.

A high fever during pregnancy may increase a woman's chances of having a baby with spina bifida. Women with epilepsy who have taken the drug valproic acid to control seizures also are at an increased risk of having a baby with spina bifida.

Types of Spina Bifida

The two forms of spina bifida are spina bifida occulta and spina bifida aperta:

Spina bifida occulta is the mildest form of the condition and can go unnoticed. "Occulta" means "hidden" in Latin, which in this case means that the defect is covered by skin. The spinal cord does not stick out through the skin, although the skin over the lower spine may have a patch of hair, a birthmark, or a dimple above the groove between the buttocks. Inside, the cord may be tethered (attached) to surrounding tissue instead of floating loosely in the spinal column.

Most babies born with spina bifida occulta do not have long-term health problems.

Meningocele (meh-NIN-guh-seel) involves the meninges, the membranes that cover and protect the brain and spinal cord. If the meninges push through the hole in the skull or the vertebrae (the small, ring-like bones that make up the spinal column), it creates a fluid-filled sac called a meningocele. This sac is visible on a baby's head, neck, or back. The sac can be as small as a grape or as large as a grapefruit, and usually is covered by a thin layer of skin. Meningoceles can happen anywhere along the spinal column or at the base of the skull.

Babies with this condition can have health problems if the nerves around the spine are damaged. For example, if the nerves that control the release of the bowels or bladder are affected, it may be difficult for a child to control these body functions. They also might have trouble moving certain muscles (paralysis). The degree of paralysis depends on where the meningocele is in the spine. The higher the opening is on the back, the more severe the paralysis can be.

Myelomeningocele (my-uh-low-meh-NIN-guh-seel) is the most severe form of spina bifida. It happens when both the meninges and the bottom end of the spinal cord push through the hole in the spine, forming a large fluid-filled sac that bulges out of a baby's back. Sometimes the sac bursts during childbirth and the spine and nerves are exposed at birth.

A baby with this type of spina bifida usually has some paralysis, and muscle or bone problems as a result of the paralysis. This is due to the abnormal development of nerves in the spine, or to nerves being stretched as a result of the defect.

It's also common for babies to have hydrocephalus, a buildup of cerebrospinal fluid in and around the brain. This causes the baby to have an enlarged head or bulging soft spot at birth, which is the result of too much fluid and pressure inside the skull.

Diagnosis

Expectant parents may be able to find out if a baby has spina bifida by taking certain prenatal tests.

The alpha-fetoprotein (AFP) test is a blood test done between the 16th and 18th weeks of pregnancy. This test measures how much AFP, which the fetus produces, has passed in the mother's bloodstream. If the amount is high, a repeat test may be done to make sure that the result is correct. If the second result is high, it could mean that a baby has spina bifida. In this case, other tests will be done to double-check and confirm the diagnosis.

In most cases of spina bifida aperta, doctors can see the defect on a prenatal ultrasound. Amniocentesis also can help determine whether a baby has spina bifida. A needle is inserted through the mother's belly and into the uterus to collect fluid that is tested for AFP.

Usually, spina bifida occulta is not found until after a baby is born. To diagnose the condition in these cases, doctors may do an ultrasound on younger babies (less than 3 months old). For older babies, and to confirm results in younger babies, doctors may rely on a magnetic resonance imaging (MRI) scan or computed tomography (CT) scan.

Treatment

Treatment for spina bifida depends on its severity. Because spina bifida can involve many different body systems, like the nervous and skeletal systems, children may need support from a team of medical professionals. This team may include doctors (such as neurosurgeons, urologists, and orthopedic surgeons), physical and occupational therapists, and social workers.

Babies with spina bifida occulta might not need any treatment, unless their spinal cord is tethered. Tethering can lead to problems later in life (during growth spurts) so it's necessary to surgically detach the spinal cord from surrounding tissue. After surgery, babies usually have no long-term health problems, but may need surgery again later in childhood if the spinal cord reattaches.

Babies with a meningocele need surgery to push the meninges back into the body and close the hole in the vertebrae or skull. This is usually done in the first few months of life.

Babies with a myelomeningocele need surgery 1 to 2 days after birth to protect the exposed area and central nervous system, and to prevent these areas from becoming infected. If a myelomeningocele is detected early enough during a woman's pregnancy, the fetus can be operated on to correct the defect during the 25th week of pregnancy. During surgery, doctors detach the spinal cord from the skin, push the spinal cord back into place, and close the opening.

Babies who have hydrocephalus also need surgery to ease the buildup of fluid around the brain. This may require an endoscopic third ventriculostomy procedure or a shunt procedure:

In a ventriculostomy, a small opening is made in the bottom of the third ventricle (one of four ventricles in the brain) to allow fluid to exit the brain.

In a shunt procedure, a thin tube is placed within the brain to drain extra fluid down to the belly, where the body can absorb it.

Outlook

After recovery from surgery, babies born with a meningocele or myelomeningocele may need long-term care to help treat any underlying conditions that result from their spina bifida. Those with paralysis may eventually need walking aids like leg braces, walkers, or a wheelchair. Children with myelomeningocele who also have hydrocephalus will need the continuing care of a neurosurgeon, and they may have learning difficulties in school that require special services.

With the right medical care, kids can go on to lead normal, active lives. The goal is to create a lifestyle for them and their families in which their disability interferes as little as possible with normal everyday activities.

Prevention

Many cases of spina bifida can be prevented if women of childbearing age take 0.4 milligrams (400 micrograms) of folic acid every day before pregnancy and continue to take it throughout the first trimester. Some women may have to take more folic acid, especially if they are taking the medicine valproic acid for epilepsy or depression.

Because many women don't find out that they're pregnant until 4 to 5 weeks into the pregnancy, it is important to start taking folic acid before becoming pregnant. This provides the best protection for an unborn baby. Good sources of folic acid include eggs, orange juice, and dark green leafy vegetables. Many multivitamins contain the recommended dose of folic acid, too.

Reviewed by: Joseph H. Piatt, MD
Date reviewed: October 01, 2016

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